Electric induction-motor.



No. 741,272. PATENTED OCT. 13, 1903. E. H. PORTER & B. CURRIER.

ELECTRIC INDUCTION MOTOR.

APPLICATION FILED PEB. 7| 1903.

N0 MODEL. 3 SHEETS-SHEET 1.

B. Currier my/.Qwn

- l E.H.1 orter Attorney me mums PETERS cu. PNQTQUTNO.. wAsumaToN. um,

No. 741,272. PATENTTO OOT. Is, 1903.

- I. II. TOIITTII O B. OIIRRIER.

OLTOTRIO IIIIIOOTION MOTOR.

APPLICATIONS FILED FEB. 7,1903.

NO MODEL. Y I Er l l i7, I C: SIETS-SHE/Z.

Witnesses 1.9 J6 J9 lnventogf,

c l E.H.Pox:ter By his B.Curr1er ttorney me Nona@ mme ce www umo..WASHINGTON. u I;

YNo. 741,272. PATENTED OCT. 18, 1903. E. H.'PORTER L B. CURRIER.

ELECTRIC INDUCTION MOTOR.

APPLICATION FILED PEB.7,1903.

l i 15 i i Attorney UNITED STATES Patented october 13, 190e.

PATENT Orricn ELECTRIC INDUCTION-MOTOR.

SPECIFICATION forming part of Letters Patent No. 741,272, dated October13, 1903. I Application filed February '7, 1903. Serial No. 142.419. (Nomndel To all whom t may concern,.-

Be it known that we, EDWIN H. PORTER and BURLEIGH CURRIER, citizens ofthe United States of America, and residents of Philadelphia, in thecounty of Philadelphia and State of Pennsylvania, have invented certainnew and useful Improvements in Electric Induction-Motors, of which thefollowing is a specification.

Our invention relates to an electric alternating-current motor which isintended, primarily, for use on electric locomotives, railroad-cars, andthe like, but may also be used as a stationary motor wherever variablespeed is desired.

The object of our invention is to vary the connections of thestator-bars of a motor of this type in such manner as to produce avariable speed through a wide range of variation, suoli as is requiredfor a railway service.

Such motors as are in common use are ordinarily adapted for use withpolyphase currents; but, as is wellunderstood, single-phase alternating`currents may also be used where starting devices are employed.

Our device for variation of speed is independent of the number of phasesof the current. a

As is wellknown,tl1e number of revolutions per minute of analternating-current motor of the synchronous or non-synchronous type isdependent on two factors-iirst, the frequency or alternations of thecurrent,and,sec ond, the number of poles of the motor. Now it isiinpracticable to vary the frequency of the circuit; but according toour invention the numberof poles of the motor is varied by throwing agreater or fewer number of ad jacent stator -bars in multiple with oneanother, according to the speed desired, and thus producing varyin gspeeds bearing a simple relation to each other, such as one, two, three,four, six, eight, twelve, and so on.

Our invention is carried out in the manner which will behereinafterdescribed and which is illustrated in the accompanyingdrawings, wherein- Figures 1 to 8, inclusive, are diagrammatic viewsshowing the successive different ways in which the stator-bars of themotor are con nectcd to the circuit of a three-phase current to producesuccessively-in creasing speeds,thc views in this ligure being' oi asetof stator-bars developed on a plane surface, the iron laminationsbeing indicated by longitudinal lines beneath. The connection of thecircuit in this case is what is known as the star7 connection. Figs. lto 8 are diagrammaticviews similar to Figs. 1 to S, but showing thecircuits connected by what is known as the delta connection. Fig. S) i'sa side elevation, partly in section, of an induction-motor equipped withour improvements forvarying the speed. Fig. 10 is a transverse sectionof one side of the motor-frame, indicating construction al details,takenon the line 10 10 ol' Fig. l). Fig. 11 is a longitudinal section on theline l1 11 of Fig'. 13 through the end of the stator-bars and theadjacent bus-bars and also lthe three-terminal switclrcontact pieces andthe operatin means therefor. Fig. 12 is a transverse section taken onthe line 12 12 oi' Fig. 11. Fig. 13 is a transverse section, on anenlarged scale, taken on the line 13 13 of Fig. 11; and Fig. 14: is aperspective viewof one of the segmental pistons.

The same numerals ol' reference denote like parts in all the Iigures ofthe drawings.

In the drawings the statorbars are indicated by the numeral 1G and thethree terminals or bus-bars of a three-phase circuit by the numerals17,18, and 19. The 'rotor is designated by the numeral 20.

The motor, as shown in Figs. 1 to S, is supposed to be connected in thewell-known star fashion, one end of the different stator-bars beingconnected to the respective bus-bars17, 18, and 19, and the other endsof the statorbars may all be connected together by a ring connection 21,thus forming the well-known star method of connecting. In some cases,however, it is desirable to use the delta connection, as shown in Figs lto S, in which case there is a second set of bus-bars, 17/ 1S 19 at theother side of the stator instead of the ring connection 21. It will beunderstood that in this case a double set of switches is to be providedto be simultaneously operated at each side of the stator but otherwisethe mode of operation is identical with the star connection, which willnow be described.

According to our invention we arrange the stator-bars with individualswitches, by

IOO

which each stator-bar may be connected to either of the three poles orbus-bars 1.7, 1S, and 19 of the circuit, and we may arrange a controllerso as to control the different groups of connections of the stator-barsnearly simultaneously, as by a movement of the control-- ler; but suchcontroller does not ferm a part of our present invention. Figs. 1 to Sillustrate a series of different modes in which the stator-bars may beconnected in a motor having one hundred and forty-four stator-bars,

`one-third of the armature only being shown diagrammatieally.

In Fig. 1 the stator-bars are connected in groups of three te therespective bus-bars 17, 1S, and lil-that is to say, there is onlyoue barper pole per phase-and there would be naturally forty-eight rotatingpoles on the stator. In Fig. 2 the bars are connected in groups ofsix-that is to say, two adjacent bars to the same bus-bar-the iirst twobeing connected, for instance, to the bus -bar 17, the next two to thebus-bar 1S, the next two to the bus-bar l), and so on, there being inthis case two bars per pole per phase and but twenty-four rotating polesin the stator, so that the magnetic field by the connection of Fig. 2will rotate twice as fast as that of Fig. il, thus producing a motor oftwice the speed. In Fig. 3 the bars are connected to the bus-bars ingroups of uine-that is to say, there are three bars per pole per phaseand but sixteen poles in the magnetic field. IIence the speed of themotor is three times that with the arrangement in Fig. 1. In Fig. 4, inlike manner, the stator-bars are connected in groups of twelve, or fourbars per pole per phase; in Fig. 5 in groups of eighteen, or six barsper pole per phase; in Fig. G in groups of twenty-four, or eight barsper pole per phase, in Fig. 7 in groups of thirty-six, or twelve barsper pole per phase, and in Fig. S in groups ef forty-eight, or sixteenbars per pole per phase-giving, respectively, in these latter casesspeeds of i'our, six, eight, twelve, and sixteen times the velocity ofthe connection of Fig. 1. Figs. 1, 2, 3, et, 5, 6, 7, and S may also betaken as representing a complete developed stator containing forty-eightbars only and connected in like manner as already described.

XVe will now describe the method which we prefer to employ for changingstator-bar connections, although this is a matter of detail which doesnot form an essential part of the principle of our invention. IVe wish,therefore, to be understood that the following description of theconstruction employed byus is not essential to our invention, as we mayuse other modes of carrying out the same.

designates the frame of a motor of any preferred construction. Thatherein shown by us, being the one in common use, is provided with anexternal stator, as 223, the stator-bars 16 of which are seated indeeplyrecessed slots 2a around the inner periphery of the stator andsuitably insulated therefrom, as

may be required. Vithin thc circular stator is mounted the rotor 35,which is j ournaled in pillow-blocks, one of which is shown at 20,rising from the end of the frame. The rotorherein shownis ofthesquirrel-cage type, being provided with rotor-bars 2S parallel to thestator-bars at stated intervals around the circumference and embedded indeep slots 20 therein, their ends being` joined by a pair et' rings, one0f which is shown at 30. It will be understood that rotors supplied withcurrent from an external source may be employed, if desired, as this isindifferent so far as our invention is concerned. The ends of thestator-bars 1U are connected at the rear side of the machine (not shownin the figure) by the ring 2l when the star connection is used, while attheir other ends (shown on the right-hand side of Fig. 9) they project aconsiderable distance,in the manner shown more clearly in Fig. 11. Thethree bus-bars 17, 1S, and 10 are formed as three complete rings, whichconnect the ends of the stator-bars together, but are insulatedtherefrom by suitable insulating-collars 3l, these bus-bars being, asshown, perforated by a series ofholes, so that they pass over andsurround the ends of the stator-bars 1U. The three rings may be formedof bar-copper and lie 011e over the other, as illustrated in Fig. 1l.,and are separated from each other by insulating-layers 32 and from theframe of the machine by a lower insulating-layer 83, while over the topof the uppermost bar lll may be placed a fourth ring of insulatingmaterial 34. rlhe ends oli' the stator-bars 16 project beyond theinsulation Si, and each is formed with a spherical concavity 35 in itsend, in which is loosely journaled a metallic ball f3 The collar ill. isformed, as shown, as part of a mold or casting of insulating material,having at its outer extremity an enlarged cylindrical casin g 337,and,furthermore, there are three depending tubular insulating-sheaths whichpass through suitable auxiliary holes in the outermost busbars 1.8 and15) and are designed for the insulation ot connectiiig-conductors Sill,which may be provided with suitable screw-threads 4:0, connecting themto their respective busbars 17,18, andl) and which, passing through thetubular appendages 38 of the casing, pass through holes in the baseportion -l-OL thereof and project also through holes termed in threesectoral metallic terminals 4:1, 42, and 4-3 andareelectricallyconneetedthercto. rlhesetcrminals are seated in recesseseach of about one hundred and twenty degrees in the base 40 and areseparated fromeaeh other by radial partition-Walls I4- ol' the casing,which extend inwardly and abut against the ball 80. The ball 30 and thestator-bar are separated from the plates 11, t2, and by insulatingmaterial Lto.

The interior of the casing 37 is of spherical. shape, concentric withthe ball 3G, and is divided into three pyramidal chambers fill, in whichtravel a set of three segmental pistons ICO ICE

ITO

47. These pistons are in close connection with the outer wall of thecasing at their external periphery and at their internal periphery withthe ball 36, so as to seperate hermetically* the two parts of each ofthe chambers 46 on the respective sides of the pistons. These pistonshave each an inwardly-extending radial tongue 4S, which passes throughand is fastened in a radial aperture in the ball 36, as shown, in' suchmanner that only one of the pistons 47 can bein its lowermost positionat the same time, as this piston, by the rolling of the ball 36, forcesthe other two pistons upwardly to the upper portion of their respectivechambers 46. The three pistons 47 are rigid with the ball whatever thedetail construction.

The upper side of the three chambers 46 of the casing 37 is closed by awasher 49, of insulating material, which fits closely against the upperside of the ball 36 and rests upon an annular shoulder 59, formed withinthe casing 37, and this washer 49 is held in place by a cylindrical plug5l, which is provided with suitable screw-threads, engaging with femalethreads formed on the inner surface of the casing 37 and which forcesthe washer 39 into place. vBoth the washer 49 and the plug 5l arepierced with a set of three tubular passage-ways 52 opposite the centersof their respective chambers 46 and which communicate with the exterior.In order to keep the passage-ways 52 formed in the washer 49 and plug 51in line with each other, the plug 5l may be formed with a plurality ofprojections or snugs 53, fitting in suitable recesses in the upper faceof the washer. This enables a firm joint to be formed and the parts tobe held securely in place, while hermetically sealing the chambers 46from each other and from the exterior.

The tubes 52 are arranged tc be connected with a set of fluid-pressuretubes 54, which may, if desired', be of flexible metal, and are securedopposite the openings of the passageways 52 in any suitable mannermas,for instance, by annular plugs 55, wedged against cones 56. This ismerely shown by way of example, as of course any suitable means may beused to connect the respective chambers 46 with a suitable source ofhydraulic or pneumatic pressure.

It will be observed that by forcing hydraulic or pneumatic pressurethrough either one of the three tubes 54, connected with the chambers46, and releasing the pressure upon the others one of the pistons 47 isforced down into connection with the terminal 4l, 42, or 43, as the-casemay be, connecting the stator-bar with the appropriate bus-bar, whilethe other pistons 47 are at the same time raised up, thus preventing ashort-circuit. The set of tubes 54 from all of the pressurechambersconnected with the stator-bars of the motor may be gathered together ina bundle and conveyed to a suitable controller or valve mechanism foroperating the proper pistons at the proper times, and thu-s making theconnections illustrated in Figs. l to 8, and l to 8.

The three bus-bars 17, 18, and i9 are shown as having each a flexibleear 57, connected with one of the three poles 58 of a terminal-board 59at the side of the motor, and the bundle of tubes 54 may be held inposition by outwardlyprojecting brackets 60, out of contact with thethree ears 57.

lVhile we have shown in the accompanying drawings the preferred form ofour invention, it will be understood that we do not limit ourselves tothe precise form shown, for many of the details may be changed in formor position without affecting the operativeness or utility of ourinvention, and we therefore reserve the right to make all suchmodifications as are included within the scope of the following claimsor of mechanical equivalents to the structures set forth.

It will of course be understood that instead of individual stator-bars,each connected singly by one of the triple switches to the bus-bars, agroup of several stator-bars or strands of wire or other like length ofconductor may be used according to the style of construction of themotor upon which our device is used, but we have described saidconductors as single bars simply because this is the most simple form ofconstruction.

Having thus described ourinvention, what we claim as new, and desire tosecure by Letters Patent, is

l. In an alternating-current electric motor, the combination of aplurality of transverse conductors adapted to carry current to produce amagnetic lield, an electric circuit of a plurality of phases, and meansfor switching the ends of said transverse conductors in multiple orderwith the different phases giving a variable number of bars per pole perphase.

2. In an alternating-current electric motor, the combination of a set ofstator-bars in inductive relation with the rotor, an electric circuit ofa plurality of phases, and means for interchangeably connecting thestatorbars with the different phases of the circuit in regular ordergiving a variable number of conductors per pole per phase.

ln an alternating-current electric motor, the combination of a set ofstator-bars in inductive relation with the rotor, a plurality of omnibusconductors located adjacent to the ends of the stator-bars, an electriccircuit of a plurality of phases connected to the respective omnibusconductors, and a set of switches adapted to connect each of thestator-bars with any of the omnibus conductors.

4. In an alternating-current electric motor, the combination of a set ofstator-bars in inductive relation with the rotor, a plurality of omnibusconductors located adjacent to the ends of the stator-bars, an electriccircuit of a plurality of phases connected to the respective omnibusconductors, a set of switches ICO IIO

III;

adapted to connect each of the stator-bars with any of the omnibusconductors, and means for throwing any of said switches for throwingeach stator-barinto connection With its appropriate omnibus conductor.

5. In an alternating-current electric motor, the combination of a set ofstator-bars in inductive relation With the rotor, a plurality of omnibusconductors located adjacent to the ends of the stator-bars, an electriccircuit of a plurality of phases connected to the respective omnibusconductors, a set of switches adapted to connect each of the stator-barsWithits appropriate omnibus conductors, and means for throwing saidswitches Jfor throwing each stator-bar into connection With itsappropriate omnibus conductors and simultaneously disconnecting the barfrom all of the other omnibus conductors.

6. Inan alternating-current electric motor, the combination of a statorhaving a set of transverse conductors, an electric circuit oi' aplurality oi' phases, means for connecting' one end of each of saidtransverse conductors to any one of said phases, and means forconnecting the other end of each transverse conductor to any other phasein desired order, whereby the stator-bars are connected in delta.

7. In an alternating-current electric motor, the combination cfa statorhaving a set of transverse conductors, an electric circuit of aplurality of phases, means for varying the connections of the transverseconductors so as to connect them at one end in desired order withdifferent phases giving a variable number of stator-conductors per poleper phase, and means for similarly variably connecting the other end ofsaid conductors to the respective phases so as to give a deltaconnection.

S. In an altern ating-current electric motor, thel combination of astator-bar, an electric circuit of a plurality of phases, aninsulatingcasing surrounding the ends of the statorbar, a plurality ofterminals Within said casing and connected to the respective phases ofthe circuit, a plurality of movable contact-pieces corresponding to therespective terminals, and means for depressing one of said contactpiecesto connect electrically the stator-bar with the proper phase.

9. In an alternating-current electric motor, the combination of astator-bar, an electric circuit of a plurality of phases, aninsulating-casing surrounding the ends of the statorbar, a plurality ofterminals Within said casing and connected to the respective phases ofthe circuit, a plurality of movable contactpieces corresponding` to therespective terminals, and means for depressing one of said contactpieces to connect electrically the stator-barwith the proper phase, eachof said contact-pieces being so connected with the others that any endof a stator-bar can only be connected With one phase at any time.

l0. In an alternating-current electric motor, the combination of astator-bar, an electric circuit of a plurality of phases, aninsulating-casing surrounding the ends of the stator-bar, a pluralityoi' terminals within said casing and connected to the respective phasesof the circuit, a plurality of movable contact-pieces corresponding tothe respective terminals, means for depressing one of saidcontact-pieces to connect electrically the stator-bar with the properphase, each oi`- said contact-pieces being so connected with the othersthat any end of a stator-bar can only be connected with one phase at anytime, said means for depressing any of said contactpieces being operablefrom a distance.

ll. In an alternating-current electric motor, the combination of astator-bar, an electric circuit of a plurality of phases, an.insulatingcasing surrounding the ends ot' the stator-bar, a plurality olterminals within said casing and connected to the respective phases ofthe circuit, a plurality of movable contact -pieces corresponding to therespective terminals, and means for depressing one of saidcontact-pieces to connect electrically the stator-bar With the properphase, each ot said contact-pieces being so connected with the othersthat any end of a stator-bar can only be connected With one phase at anytime each oi' said contact-pieces being operated as a piston moving in aclosed chamber, a tubular port connected With said chamber at one sidethereof, and means for introducing pressure into said chamber to movesaid contactpiece.

l2. In an alternating-current electric motor, the combination of astator-bar having a projecting end and a spherical concavity therein, ametallic ball freely rotatable in said cavity, an insulating-casingsurrounding the end of said stator-bar, a plurality of terminalpieceslocated in the base of said casing surrounding said stator-bar andinsulated therefrom, a plurality of phases connected to the respectiveterminals, a plurality of closed chambers formed in said casing andseparated from each other by insulating-Walls, a plurality of segmentalpistons movable in the respective chambers and electrically connectedwith said ball, and means for depressing any one of said pistoncontact-pieces into contact with its respective terminal.

13. In an alternating-current electric motor, the combination of astator-bar having a projecting end and a spherical concav-ity therein, ametallic ball freely rotatable in said cavity, an insulating-casingsurrounding the end of said stator-bar, a plurality of terminalpieceslocated in the base of said casing surrounding said stator-bar andinsulated therefrom, a plurality of phases connected to the respectiveterminals, a plurality of closed chambers formed in said casing andseparated from each other by insulating-walls, a plurality of segmentalpistons movable in the respective chambers and electrically connectedWith said ball, and means for depressing any one of said pistoncontact-pieces into Contact ICS IIO

with its respective terminal, each of said pistons being` so connectedwith the others that when it is depressed the other two are forcedupwardly out of contact with their respective terminals.

la. In an alternating-currcnt electric motor, the combination of astator-bar having a projecting end and a spherical concavity therein, am etallic ball freely rotatable in said cavity, an insulating-casingsurrounding` the end of said stator-bar, a plurality of terminalpieceslocated in the base of said casing surrounding` said stator-bar andinsulated therefrom, a plurality of phases connected to the respectiveterminals, a plurality of closed chambers formed in said casing` andseparated from each other by insulating-Walls, a plurality of tubularpassage -Ways formed in said casing and connected with the respectivechambers above said pistons, and means for independently introducinghydraulicor pneumatic pressure through the passage-Ways into therespective chambers to depress the respective piston contact-pieces intoContact With their respective terminals.

l5. ln an alternating-current electric motor, the combination of astator-barhaving` a projecting` end and a spherical concavity therein, ametallic ball freely rotatable in said cavity, an insulating-casing`surrounding the end of said stator-bar, a plurality of terminalpieceslocated in the base of said casing surrounding,` said stator-bar andinsulated therefrom,a plurality of phases connected to the respectiveterminals, a plurality of closed chambers formed in said casing andseparated from each other by insulating-Walls, a plurality of tubularpassage-Ways formed in said casing and connected with the respectivechambers above said pistons, means for independently introducinghydraulic or pneumatic pressure through the passage-Ways into therespective chambers to depress the respective piston contact-pieces intocontact with their respective terminals, and means for preventing, morethan one of said pistons from being,` depressed atonetime,substantiallyas described.

In testimony whereof We have hereunto set our hands and aitixed ourseals this i3d day of February, 1903.

EDVIN ll. PORTER. [n s] BURLEIGH CURRIER. L. s.'

Witnesses:

CHARLEs E. LEX, WM. R. SrfioKHoUsE.

